Power transmission



F.'T. HARRINGTON 2,366,398

POWER TRANSMISSION Filed Mm 22, 1940 Jan. 2, 1945.

. 156 .48 Z I L I INVENTOR FERRIS T. HARRlNGTON ATTORNEY Patented Jan.2, 1945' POWER TRANSIVHSSIWN Ferris Harrington, Detroit, Mich, assignorto Vickers Incorporated, Detroit, Mich... a corporation of MichiganAppiicati on T/iarch 22, 1940, Serial No. 325,276

10 Claims. on. ce-ssi This invention relates to power transmissions,

particularly to those of the type comprising two or more fluid pressureenergy translating devices one of which may function as a pump andanother as a fluid motor.

The invention is more particularly concerned with a. power transmissionsystem adapted for operation of an indexing device such as is comv monlyused with machine tools where it is desired to index a work support orother shiftable member into any one of a plurality of predeterminedpositions in sequence.

It is an object of the present invention to provide a hydraulic powertransmission system having a'hydraulic motor for operating an indexablemember together with improved mechanism for operating a shiftablepositioning pin in inter.- locked sequence with the operation of thehydraulic motor.

A further object is to provide an improved system of this characterwherein an indexa-ble member is automatically decelerated at the end ofeach indexing movement together with improved porating a preferred formof the present inven-' tion.

Referring now to the drawin there. is shown tank it by conduit 36'. Oneof the motor ports 38 of valve 30 connects by a conduit dd with the headend oi the cylinder 26. The conduit 68 has a branch at which may beconnected with some other work circuit later to be described.

The cylinder 26 carries slidably mounted therein a piston 3G having arod 46 which constitutes the usual positioning pin or locking pincustomarily provided with indexing tables as utilized in the machinetool art. When in the position illustrated, the pin 56 engages in one ofa plurality the rod end of the cylinder 26 whenever the piston the pin55 from the notch 48. 'I'he'port 52 cona pump it] adapted to be drivenby a suitable prime mover, such as an electric motor l2. The

pump l0 has a suction conduit I4 adapted to withdraw fluid from a tankI6 which is delivered "through a delivery conduit l8. The latter has aconventional relief valve 20 incorporated therein for the purpose ofbypassing to tank through a conduit 22 thewfluid deliveredby the pumpwhenever a'predetermined pressure is exceeded in the delivery conduitl8. Y

The conduit l8 has a branch 24 which forms a continuously openconnection to the rod end of 31a positioning pin actuating cylinder 26.The coni"duit l8 also extends to the pressure port 28 of afsolenoid-actuated, four-way valve 30. The latter has tank ports 32 and34 which connect with the 5 which is normally closed oil from the ports78 nects by a conduit 56 with the inlet port 56 of a. rotaryfluid motor58. A check valve B0 is incorporated in the conduit 54 for free flowfrom the port 52 tothe port 56. The driving shaft 62 of the motor 58carries a pinion 6d meshing with a large ring gear 66 secured to therotary table 53.

A branch supply conduit 68 extends from the.de-' livery conduit 50through a check valve ill to the,

conduit 54 beyond the check valve Bii.

The motor 58 has an outlet port 12 which connects by a conduit 74 with apressure-responsive valve'ifi entering the same at a port 18. A port ofth valve 18 which is always in communication with the port 18 extends bya conduit 82 to the inlet port of a hydrostatic flow-controlling Theoutlet port of the latter is convalve 84. nected to the tank conduit-35by a branch conduit 86. The valve 84 comprises a fixed but anjustablethrottle 88 together with a hydrostatic flow-regulating valve 90arranged in series between the inlet and outlet ports of the valve. The

valve 90 is regulated by means of a piston 92 and spring 94 to maintaina constant pressure drop The valve is is provided with a third port looand 85 by means of a .slidable spool valve I02. The latter is normallyurged to the left by a spring I04 adjustable by means of, a screw I06.The spool I02 is in hydraulic balance with respect to the pressure inports 18 and 60. A small piston I08 is provided at the lefthand end ofthe valve and has its left end in communication with the port 18 througha branch conduit I I0. The action is such that whenever a predeterminedpressure is exceeded in the port 16 the spool I02 will be shifted to theright against the force of spring I04 to connect port I with ports 18and 80.

The valve 16 is further provided with a connection II2 communicatingwith the space at the lefthand end of the spool I02. This connectioncommunicates by means of a conduit 4 with the valve port II6 of four-wayvalve 80. Thus,

whenever pressure is admitted to the conduit II 4 the fluid reacts overthe entire lefthand area of the spool I02 overcoming the force of springI04 and shifting the spool I02 to the right. The port, I00 of valve 16is connected to tank by a branch conduit II8.

The pump I0 may be utilized for supplying operating fluid to a separatework circuit through the branch 42. Such a circuit may comprise acylinder-and-piston motor I20 for actuating a machine tool slide inadvancing and returning strokes. The supply of fluid to the motor I20may be controlled by a panel I22 of conventional form adapted to beoperated by solenoids I24 and I26- The former, when energizede may causethe motor I20 to perform an advancing stroke, and the latter, whenenergized, may cause it to perform a returning stroke. Themovableelement of motor I20 may carry a cam. I28 for actuating limit switchesI80 and I32 at the respective ends of its stroke. Since the details ofthe separate work circuit are well known in the art and by themselvesform no part of the present invention, no further description thereofwill be given.

The four-way valve 30 has a shiftable spool I34 which is shifted to theposition illustrated whenever a solenoid I36 is energ zed. The spoolremains in this position until it has been shifted back to the left byenergization of a solenoid I38. Suitable detent mechanism, notillustrated. may be supplied for retaining the spool in its shiftedposition at either end of its movement.

For the purpose of controlling the energization of solenoids I24,control circuit is provided as follows: A momentary-contact,push-button, starting switch I40 is connected between one side of asuitable supply line L -and the coil of a holding relay I42 by a,conductor I44. The latter has holding contacts which connect by means ofa conductor I46 with a limit switch I46 having its other side connectedto the line L and adapted to be closed by one of a plurality of cams I50positoned on the indexing table 50. The cams I50 are arranged to closethe limit switch I48 when the table 50comes to rest in each one of itspredetermined positions.-

Th relay I42 has its controlled contacts connected in a circuit whichextends from line L through limit switch I30,.and by a conductor I52 anda conductor I54 to the solenoid I86, .the other side of which isconnected to line L. Thus,

- the solenoid I 86 is energized by this circuit when- -ever bothllmit'switch' I80'and relay I42 are closed,

A seciind limit the table 50 and is so positioned as to be closed bv thepas a e o each of the cams I50 at an' The switch I48 is normally openswitch m is moantea adjacent" ductor I58 to the operating coil of aholding relay I62. The holding circuit of the latter extends by aconductor I64 to the conductor I52 so that the relay I62 will remainclosed so long as the limit switch I30 remains closed. The controlledcontacts of the relay I62 are in a circuit extending from conductor I46,which is under the control of limit switch I48, by a conductor I66 and aconductor I68 to the solenoid I24 of panel I22.

The limit switch I32 is connected between line L and a conductor Iextending to the solenoid I26. A branch conductor I12 extends fromconductor I44 to a snap-acting, manually-controlled, ofi-on switch I14,the other side of which is connected by a conductor I16 to the conductorI10.

In operation, assuming the motor I2 to be driving the pump I0 and thatthe motor I has just completed a etum stroke to close the limit switch Iand that the switch I14 is in the position shown on the drawing, thesolenoid I36 will have been energized by switch, I30 through the circuitI52, conductor I64, relay I42, and conductor I54. The relay I42 be inits closed position by reason of having been previously energized ,whenthe motor I20 completed the end of I26, I36 and I88, an electric itsadvancing movement and .closedlimit switch I32. This energized the coilof relay I42 through conductor I16, switch I14 and conductor I12. Whenthe relay I42 closed ,it established its own holding circuit through theconductor I46 and limit switch I48 which would not have opened duringthe return movement of the motor -I 20.

Thus when the limit; switch I30 is closed at the end of its returnmovement the solenoid I36 is energized to shift the spool I34 to theright and all the parts will lie in the position illustrated on thedrawing. The full pump delivery is now directed through branch deliveryconduit 24to the rod end of cylinder 26 forcing the piston 44 downwardlyand causing the oil to discharge from the head end of cylinder 26through conduit 40, port 38 and port 34 of valve 30, and conduit 36 tothe tank. At the same time pressure oil is admitted through port 6 andconduit II4 through connection II2 of valve 16 thus shifting the spoolI02 to the right and opening port I00 to free communication with port18.

Accordingly, as soon as piston 44 has completely moved downwardly andretracted the locking pin 46, the port 52 opens admitting the pumpdelivery to the conduit 54 where' it flows through check valve 60 to theinlet port 56 of motor 58. The latter rotatesdriving the table 50 anddischarges oil from the outlet port 12 through conduit 14, ports 18 andI00 of valve 16, and conduit II8 to the tank I6. The motor 58accordingly rotates at full speeddetermined by the relative displacementof pump I0 and motor 58, thus I rotating the table 50 until such time asthe next cam I50 contactsthe limit switch I56.

In the meantime, however, thecam I50 which was underneath limit switchI48 "ridesout from under it thus openingthe holding circuit of relay I42permitting the latter to solenoid I36. Accordingly,

drop anddeenergizing by conductor I56 directly to the solenoid I38 thuscausing the spool I34 to shift to the left connecting port II6 to tankport 32 and connecting when the limit switch I56 closes, a circuit'isestablished from line L a motor I28 to perform an advancing stroke.

to shift to the left and would, but for the piston I I88, cause theentire motor discharge coming through conduit I4 to pass to tank throughthe flow-controlling valve 84. This would create sudden change in speedof the motor 58 which is avoided by the action of piston I88 which makesthe valve I8 act. as a relief valve so that the pressure in conduits I4and 82 can never rise beyond a predetermined value during this action ofdeceleration. Accordingly, until a large portion of the potential energyin the mass'of the table 58 is dissipated, the valve I8 acts as a reliefvalve bypassing whatever quantity is necessary from the conduit 14 tothe tank through port I88 and conduit I I 8. In this way a predeterminedbraking effect is provided on the fluid motor 58' until such t me as theinertia of the table 58 has been absorbed. Thereafter, the motor 58continues to rotate at a speed determined by the setting of the throttle88 in valve 84.

It will be noted that during this decelerating actionof motor 58 theinlet thereof is connected to the pump delivery line I8 through port 28and port 38 of valve 38, and through conduit 48 and branch deliveryconduit 68, the check valve "I8 permitting free flow to the motor 58 bythis path. It will also be noted that check valve 88 prevents back flowtoward the port 52 in cylinder 28.

The shifting of the valve 38 also directed the pump delivery throughconduit 48 to the head end of cylinder 28 where, due to the greaterarea,

- this pressure oil is able to shift the piston 44 up! wardly againstthe corresponding pressure exerted in the top end of cylinder 28 overthe smaller top area of piston 44. During the deceleration and slowspeed operation of motor 58. the latter will not utilize the fulldelivery of pump I8. A portion of the excess delivery is'utilized tooperate the piston 44, and any remainder is bypassed to tank by reliefvalve 28. Thus the shifting of valve 38 accomplished two functions;

first, it provided for deceleration of the motor completes its advancingstroke switch I3: is contacted energizing solenoid I28 to reverse motorI28 and also causing the relay I42 to pick up in preparation forinitiation of another indexing cycle when the motor I28 has againreturned and closed limit switch I38 as previously described. Aftermotor I28 starts to the right, switch I32 will open, but, due to thefact that switch I48 is closed, the holding circuit for relay I42 isclosed so that, as soon as motor I28 closes switch I38, solenoid I38will be energized. The system thus repeats its cycles of movement,first, of the indexing table 58, and then, of the auxiliary work circuitfor the motor I28, so long as the switch "4 remains in the positionillustrated,

When it is desired to stop the machine, the switch I14 may be opened,thus preventing energization of the relay I42 as the motor I28 completesits advancing stroke. Accordingly, when it completes its return stroke,the solenoid I38 will not be energized, and the machine will come torest. In order to again start the machine on repeating cycles it isnecessary to close the switch I14 and thereafter to depress the startingswitch I48 in order to pick up the relay I42. If it is desired to startthe machine through a single cycle only the switch I" may be left open,and then when switch I48 is momentarily closed the same cycle ofmovements will take place except that relay I42 will not be picked up atthe end of the forward stroke of motor I28. Accordingly the machine willcome torest when motor I28 returns to the position illustr'ated.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other forms Imight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. In a hydraulic power transmission system for indexing a member to aplurality of predetermined stations in sequence the combination throughconductors I58 and I88. As the relay I82 picks up it establishes itsholding circuit Q through conductor I84 and conductor I52 to the limitswitch I38 which at this time is closed by reason of the motor I28 lyingin its fully returned position. Relay I82 accordingly stays up and es-.

tablishes connection between conductors I88 and I58, which conductorsare not made alive at the present time, however, due to theopen gap atlimit switch I48. A short distance after the cam I passes under thelimit switch I58, which distance is great enoughto permit deceleration'of table 58, another cam I58 contacts the limit switch I48 thus closingthis gap and energizing the solenoid I24 of the panel I22 to cause theThe locking pin 48 retains the table 58 in its indexed position duringthis movement of motor I28. As soonas motor I28 starts to the left,limit switch I38 opens to break the holding circuit for relay of asource of pressure fluid, a fluid motor connected to drive the member,supply and return connections between the motor and the source, a lockbolt for locking the member in any station, means for shifting the lockbolt between locking and releasing position, valve means for initiatingthe supply of fluid to" the motor, a valve in the return conduit forrestricting the flow of fluid exhausting from the motor, valve means forfreely bypassing the'restricting valve during a portion of an indexingcycle whereby when the bypassing valve is closed the restricting valvewill decelerate the motor, and means for limiting to a predeterminedvalue the pressure between the motor and the restricting valve duringthe decelcrating periods.

2. A hydraulic .power transmission system for driving a member having alarge degree of inertia comprising in combination with a source ofpressure fluid, a fluid motor connected to drive the member, supply andreturn conduits between the motor and the source, valve means forinitiating the supply of fluid to the motor, a hydrostaticflow-controlling valve in the return conduit for restricting the flow offluid exhausting from the motor to a predetermined rate independently ofexhaust pressure, valve means for freely bypassing the restricting valveto operate the motor at full speed, and means for limiting to apredetermined value the pressure between the motor and the restrictingvalve during times while the bypass valve is not freely bypassing therestricting valve whereby the motor may be decelerated after full speedoperation, said bypassing valve and said pressure limiting meansconstituting a single valve having a single shiltable flow controllingmember.

3. A hydraulic power transmission system for driving a member having alarge degree of inertia comprising in combination with a source of.pressure-fluid, a fluid motor connected to drive the member, supply andreturn conduits between the motor and the source, valve means forinitiating the supply of fluid to the motor, a hydrostaticflow-controlling valve in the return conduit for restricting the flow offluid exhausting from the motor to a predetermined rate independently orexhaust pressure, valve means for freely bypassing the restricting valveto operate the motor at full speed; means for limiting to apredetermined value the pressure between the motor and the restrictingvalve during times while the bypass valve is not freely bypassing therestricting valve whereby the motor may be decelerated after full speedoperation, said bypassing valve and said pressure limiting meansconstituting a single valve-having a single shiftable flow-controllingmember and having two pilot-operating chambers for shifting theflow-controlling member, means connecting one chamber to the supplyconduit, and .means connecting the other chamber to the return conduit.

4. A hydraulic power transmission system for driving a member havingalarge degree of inertia comprising in combination with a source ofpressure fluid, a fluid motor connected to drive/the member, supply andreturn conduits between the motor and the source, valve means forinitiating the supply of fluid to the motor, a hydrostaticflow-controlling valve in the return conduit for restricting the flow offluid exhausting from the motor to a predetermined rate independently ofexhaust pressure, valve means for freely bypassing the restricting valveto operate the motor at full speed, and means for limiting to apredetermined value the pressure between the motor and the restrictingvalve during times while the bypass valve is not freely bypassing therestricting valve whereby the motor may be decelerated after full speedoperation.

5. In a hydraulic power transmission system for indexing a member to aplurality of predetermined stations in sequence the combination of asource of pressure fluid, a fluid motor connected to drive the member,supply and return connections between the motor and the source, a lockbolt for locking the member in any station, hydraulic means including acy1inder and piston for shifting the lock bolt between locking andreleasing position, said motor being connected to receive fluid from thesupply conduit only after such fluid has passed through said hydraulicmeans for one direction of bolt shifting, means for blockingflow fromthe hydraulic means to the motor and controlled by a predeterminedtravel of the bolt to permit such flow when the bolt is completelyshifted in said one direction, and means connecting the motor andhydraulic means in parallel for the other direction of bolt shifting. 4

6. In a hydraulic power transmission system for indexing a member to aplurality of predetermined stations in sequence the combination of asource of pressure fluid, a fluid motor connected to drive the member,supply and return connecdraulic means including ac'ylinderand piston forshifting the lockbolt between locking and releasing position, said motorbeing connected to receive fluid from the supply conduit only after suchfluid has passed through said hydraulic means for one direction 0! boltshifting, means for blocking flow from the hydraulic means to the motorand controlled by apredetermined travel of the bolt to permit such flowwhen the bolt is completely shifted in said one direction, a check valvebetween the hydraulic means and the motor arranged to permit-flowtoward-the motor, and means connecting the motor and hydraulic means inparallel for the other direction of bolt shifting.

'7. In a hydraulic power transmission system for indexing a member to aplurality of predetermined stations in sequence the combination of asource of pressure fluid, a fluid motor connected h drive the member,supply and return connections between the motor and the source, a lockbolt for locking the member in any station, hydraulic, means including acylinder and piston for shifting the lockbolt between locking andreleasing position, said motor being connectedvto receive fluid from thesupply conduit only after such fluid has passed through said hydraulicmeans for one direction of bolt shifting, means for blocking flow fromthe hydraulic means to the motor and controlled by a predeterminedtravel of the bolt to permit such flow when the bolt is completelyshifted in said one direction, means connecting the motor and hydraulicmeans in parallel for the other direction of bolt shifting, and a checkvalve in said connecting means opening to permit flow toward the motor.

8. A hydraulic power transmission system for indexing a member to aplurality of predetermined stations in sequence comprising incombination with a source of pressure fluid, a fluid motor connected todrive the member, supply and return connections between the motor andthe source, a lock bolt for locking the member in any station, adifl'erential area cylinder and piston device for shifting the lock boltand having its smaller area connected to the supply conduit to themotor, valve means responsive to retraction of the bolt for opening' thesupply conduit to flow to the motor, a branch supply conduit extendingto the motor independently or said valve means, and having a connectionto the larger area of said device, a selectively shiftable valvearranged to connect the branch supply conduit either to thefirst-mentioned supply conduit or to exhaust the same, andmeansresponsive to shifting of the last-mentioned valve for concurrentlyrestricting the return conduit from the motor while the branch supplyconduit is connected to the flrstmentioned supply conduit.

9. A hydraulic power transmission system for indexing a member to aplurality of predetermined stations in sequence comprising incombination with a source of pressure fluid, a fluid motor connected todrive the member, supply and return connections between the motor andthe to the motor, a branch supply conduit extending V to the motorindependently of said valve means, and having a connection to the largerarea of said device, a selectively shittable valve arranged to connectthe branch supply conduit either to the first-mentioned supply conduitorto exhaust the same, check valves in each supply conduit to prevent backflow from the motor, and means responv -sive to shifting of thelast-mentioned valve forconcurrently restricting the return conduit fromthe motor .while the branch supplyconduit is connected to thefirst-mentioned supply conduit.

10. In a hydraulic power transmission system forindexing a member to aplurality of 'predetermined stations in sequence the combination of asource of pressure fluid, a fluid motor connected to drive the member,supply and return connections between the motor and the source, a lock10 trical mean until fully released. 7

FERRIS T. HARRINGTON.

